Electrical properties of PZT thin films with Ir and IrO/sub 2/ electrodes

The development of ferroelectric memory devices requires an understanding of the fatigue properties of ferroelectric thin films. PZT thin films by sol-gel method on Pt/Ti with residual polarization reduced by continuous polarization reversal about 10/sup 8/ cycles. In this paper, we regard Ir, IrO/sub 2/ and these layer films as electrode materials and have evaluated the electric characteristic of PZT thin film capacitors. Regarding the ferroelectric material, we used PZT(Zr/Ti=52/48) by sol-gel method. By using Ir and IrO/sub 2/ electrodes, the diffusion barrier effect becomes very good, therefore they can prevent Pb and other elements from diffusing into the electrode and polycrystalline silicon (poly-Si). PZT thin films using Ir/IrO/sub 2/ layer electrodes show no fatigue up to 10/sup 12/ cycles of /spl plusmn/5 V switching pulses.